From: Bruce Momjian <bruce@momjian.us>
Message-Id: <200611221814.kAMIE6Y08930@momjian.us>
Subject: Re: Replication Docs
In-Reply-To: <45649100.4040505@bluegap.ch>
To: Markus Schiltknecht <markus@bluegap.ch>
Date: Wed, 22 Nov 2006 13:14:06 -0500 (EST)
CC: pgsql-docs@postgresql.org, emmanuel.cecchet@continuent.com
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Markus Schiltknecht wrote:
> Hi,
> 
> Bruce Momjian wrote:
> > OK, it is two separate entries now:
> > 
> > 	http://momjian.us/main/writings/pgsql/sgml/high-availability.html
> 
> Yes, that's fine with me.

Good.

> > Uh, good point.  The title is now "Statement-Based Replication
> > Middleware".  That doesn't say multi-master, but it doesn't say
> > master/slave either.  The Sequoia PDF you sent me is very detailed:
> > 
> >   http://www.continuent.org/uploads/sequoia/Resources/2006-08-15Cecchet_ApacheConAsia2006.pdf
> > 
> > I think we are back to the issue of classification.  We have traditional
> > master/slave as slony, and multi-master as perhaps pgcluster, and lots
> > in between.  I am thinking pgpool and sequoia fit in there.  I have
> > added Sequoia to the Statement-Based Replication Middleware section.
> 
> I'll look into that shortly, but I think Emmanuel can better categorize 
> sequoia, I've CCed him. I'd certainly categorize it as Multi Master 
> Replication (like pgpool, only that it's a poor implementation).

OK, let's see what they say.  Right now, middleware is a separate
section.

> Good, that sounds better for me.
> 
> There's only a typo at the very end:
> 
> "..conflict resolution rules. rules."

OK, fixed, thanks.

> > Uh, if the data isn't partitioned, what value is there to hitting
> > multiple servers, for single query?  I am confused.
> 
> Right, makes only sense for complex queries, i.e. when having multiple 
> seq scans and/or joins. The executor would have to be super clever for 
> such things to happen. Just forget about my comment.

Oh, I see, splitting I/O load even with multiple copies --- interesting,
but seems too far out for this documentation, as you suggested above.

-- 
  Bruce Momjian   bruce@momjian.us
  EnterpriseDB    http://www.enterprisedb.com

  + If your life is a hard drive, Christ can be your backup. +